Dna Sequencing In

A DNA sequencing method has been developed whereby DNA that has been cloned in a single-stranded bacteriophage vector can be sequenced from both ends. The method involves f i r s t making a minus-strand sense template from a single-stranded insert in the vector MJ3mp2 using a flanking primer~ and then sequencing the synthesized template using the d i d e o x y n u c l e o t i d e termination method (Sanger e t a l . , 1977~ 1980) with a second primer. Special conditions are descr ibed under which the f i r s t primer is easily removed after making the templat% and sequencing in the opposi te d i r ec t ion can be done in the normal way (Sanger e t a l . , 1980) without separa t ing the double s t rands . This method renders it possible to read up to twice the amount of sequence data from a long insert and also to check short inserts by producing complementary sequence patterns.